All Figures

$\begin{figure} \par\includegraphics[angle=270,width=7.7cm,clip]{2773fig1.ps} \end{figure}$ Figure 1: Width of the region over which 99% of the stellar radiation is absorbed as function of $\epsilon$ .
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=16.1cm,clip]{2773fig2.ps} \end{figure}$ Figure 2: Photospherical height H ( $\tau _{\rm s}=1$ ) of the inner rim for different values of $\epsilon$ , as labelled. The curves have been computed for a star with $T_{\star}=10~000$ K, $M_{\star} = 2.5~ M_{\odot}$ , $L_{\star}=47 ~L_{\odot}$ . Each curve ends where the rim becomes optically thin to the stellar radiation.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.2cm,clip]{2773fig3.ps} \end{figure}$ Figure 3: Effective temperature (i.e., $T(\tau _{\rm d}=2/3)$ ) along the rim surface for different values of $\epsilon$ , as labelled. Each curve is plotted as function of $R/R_{\rm in}$ , where $R_{\rm in}$ is the distance of the rim from the star on the disk midplane. Note that, in fact, not only R but also z changes along each curve, as shown in Fig. 2. For $\epsilon > \epsilon _{\rm cr} \simeq 0.58$ $T_{\rm eff}$ is almost independent of the grain opacity.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.9cm,clip]{2773fig4.ps} \end{figure}$ Figure 4: Near infrared emission of the curved rim (integrated between $1.25 {-} 7 ~\mu\rm m$ and normalized to $L_\star$ ) for different inclination angles and different values of $\epsilon$ . Starting from the bottom, the curves refer to $\epsilon = 0.08$ (long-dashed), 0.14 (short-dashed), 0.25 (dotted), $0.58=\epsilon _{\rm cr}$ (short-dash-dotted), 0.92 (long-dash-dotted). For the last two values of $\epsilon$ the emission is almost the same and the lines overlap. The continuum line plots the emission of the vertical rim, computed for $\epsilon = \epsilon _{\rm cr}$ .
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=17.8cm,clip]{2773fig5.ps} \end{figure}$ Figure 5: Synthetic images of the curved rim for different values of $\epsilon$ and inclination angle ( $i=0^\circ$ is face-on); comparison with the vertical rim. The left and central panels show the images of the curved rim calculated for $\epsilon = 0.08$ (silicate grains with radius $a=0.1~\rm\mu m$ ) and $\epsilon = \epsilon _{\rm cr} = 0.58$ ( $a=1.3 ~\rm \mu m$ ). The right panels show the images for the verical rim calculated for $\epsilon = 0.58$ . The surface brightness of the rim, plotted in colors, is computed for a wavelength of $2.2 ~\rm \mu m$ . The stellar parameters are as in Sect. 3, the distance is $d=144~\rm pc$ . The vertical rim for $i=0^\circ$ has zero brightness. Note that as discussed in Sect. 3 for $\epsilon >\epsilon _{\rm cr}$ the images of the curved rim remain the same.
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In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{2773fig6.ps} \end{figure}$ Figure 6: Histogram of the observed values of $L_{\rm NIR}/L_\star$ for a sample of 16 Herbig Ae stars from Natta et al. (2001) and Dominik et al. (2003). Note that the Dominik et al. values are computed between 2 and 7 ${\mu }$ m, while those from Natta et al. between 1.25 and 7 ${\mu }$ m. The uncertainties are in most cases rather large, due to the subtraction of the photospheric flux, which contributes significantly to the observed ones at short wavelengths, and to variability (see Natta et al. for some examples).
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.7cm,clip]{2773fig7.ps} \end{figure}$ Figure 7: Behaviour of the inner radius of the rim for different values of $\epsilon$ , evaluated for the star and disk parameters described in Sect. 3. Note that for $\epsilon \protect \ga \epsilon_{\rm cr} \sim 0.58$ (corresponding to silicate grains of $1.3~\rm \mu$ m) the radius of the inner rim is almost constant around 0.5 AU.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{2773fig8.ps} \end{figure}$ Figure A.1: Temperature as function of the optical depth to the stellar radiation $\tau _{\rm s}$ for small grains ( $\epsilon = 0.08$ ) and very large grains ( $\epsilon =1$ ). The dashed curves are the results of the radiation transfer code, the solid lines the temperature obtained from Eq. (1).

In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{2773fig9.ps} \end{figure}$ Figure A.2: Comparison of the SED computed with the radiation transfer code (dotted lines) and as a black-body at $T(\tau _{\rm d}=2/3)$ from Eq. (1) (solid line) for $\epsilon = 0.08$ and $\epsilon =1.0$ , as labelled.

In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{2773fi10.ps} \end{figure}$ Figure A.3: Temperature profile for grains with $\epsilon = 0.08$ , when scattering is included ( $\tilde{\omega}=0.7$ ; dashed line) or suppressed ( $\tilde{\omega}=0.0$ ; solid line).

In the text

$\begin{figure} \par\includegraphics[angle=270,width=7.7cm,clip]{2773fig1.ps} \end{figure}$	Figure 1: Width of the region over which 99% of the stellar radiation is absorbed as function of $\epsilon$ .
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$\begin{figure} \par\includegraphics[angle=270,width=16.1cm,clip]{2773fig2.ps} \end{figure}$	Figure 2: Photospherical height H ( $\tau _{\rm s}=1$ ) of the inner rim for different values of $\epsilon$ , as labelled. The curves have been computed for a star with $T_{\star}=10~000$ K, $M_{\star} = 2.5~ M_{\odot}$ , $L_{\star}=47 ~L_{\odot}$ . Each curve ends where the rim becomes optically thin to the stellar radiation.
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$\begin{figure} \par\includegraphics[angle=270,width=7.7cm,clip]{2773fig7.ps} \end{figure}$	Figure 7: Behaviour of the inner radius of the rim for different values of $\epsilon$ , evaluated for the star and disk parameters described in Sect. 3. Note that for $\epsilon \protect \ga \epsilon_{\rm cr} \sim 0.58$ (corresponding to silicate grains of $1.3~\rm \mu$ m) the radius of the inner rim is almost constant around 0.5 AU.
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